| The most common materials used for medical bed sheets, surgical gowns, medical drapes and other medical textiles are cotton and polyester fiber. It is well known that these medical textiles are easily polluted by dirt and absorb fungi. Meanwhile, sweat and sebum will provide nutrition for bacteria, which will cause bacterial infection and damage fiber. Therefore, it is necessary to develop textiles which are functioned by self-cleaning durable antibacterial.Photocatalysis is a truly environmentally friendly process where irradiation, either near UV or solar light,promotes photoexcitation of semiconductor solid surfaces. TiO2 is widely used for the photocatalysis because of its excellent optical properties, long-term stability, nontoxicity, and relatively low cost. However, TiO2 mainly absorbs UV with <380 nm wavelengths, which covers only 5% of the solar spectrum. Therefore, a new visible-light photocatalyst that extends the absorption-wavelength range into the visible-light region is of great interest to develop. Constant efforts are being taken in the last years to shift the activity of TiO2 toward the visible range and improve washing durability of fabrics modified by TiO2 nanoparticles.This study aimed to increase the photocatalytic efficiency and durability of functional fabrics based on doping TiO2 and in situ composition by ultrasonic. First, this stydy reported that doping TiO2 with SiO2 and graphene oxide. The surface areas of the TiO2/SiO2 composites were higher than that of the TiO2 due to the high surface area of the SiO2 support, and the higher effective surface are available for adsorption of reactants on the photocatalyst which leads to the higher photocatalytic degradation. In addition, a charge imbalance bringing about the creation of Lewis acidic sites: under this condition, a higher amount of hydroxide ions can be absorbed on the surface of particles conduce a higher photocatalytic efficiency. Also there are some interpretationspertinent to the mechanism of positive effects of graphene oxide on the photocatalytic efficiency of TiO2.(1)Extending light absorption: the role of the graphene act as a sensitizer(electron donor).In that case, electrons excited by sunlight in localized sp2 states of the graphene would be injected into the conduction band of TiO2;(2)Suppressing charge recombination: Graphene can act as an acceptor of the photo-generated electrons for TiO2 particles and ensure a fast charge transportation in view of its high conductivity. As a result, an effective charge separation can be achieved. In the TiO2/GO composite, the portion of graphene plays a role for conducting electrons, which makes the photocarrier transferring to the surface of graphene, and improves the separation of the electron- hole pairs and also the photocatalytic efficiency. The photocatalytic activity of samples coated with TiO2, TiO2/Si O2 and TiO2/GO was investigated quantitatively by exposing samples containing adsorbed MB to visible-light irradiation. According to the obtained results, the degradation rate of MB for TiO2/SiO2 and TiO2/GO is 31% and 40% respectively compared to10% for pure TiO2, which can be seen that composites have an enhancement on the efficiency of the photocatalyst applied to textiles.In order to further improve the photocatalytic activity of fabrics in visible light the TiO2/Si O2/GO coated fabrics were prepared to show superior photocatalytic activity under visible-light as compared to TiO2/Si O2 and TiO2/GO coated fabrics baesed on the synergistic effect of SiO2, graphene oxide and TiO2. The addition of GO was to enhance adsorbing capacity of the photocatalyst and its activity toward visible light decreasing the Eg value. Furthermore, the photocatalytic self-cleaning properties have been investigated by the degradation of methylene blue under visible-light irradiation, and the results showed that the degradation rate was 92% for TiO2/Si O2/GO coated fabrics, which proved the superior photocatalytic activity under visible-light.In the view of prepartion method, the ultrasonic was used in situ synthesis of TiO2/SiO2/GO on fabrics. In the sonosynthesis of nano-TiO2/Si O2/GO composites, an acoustic cavitation process can generate an ephemeral localised hot zone with extremely high temperature and pressure.These swift changes may lead to the sonolysis of water forming OH? and H? radicals. Overall, the generation of nano-TiO2/SiO2 composites are mainly due to transient localised hot zone,microturbulence, and shock waves.In addition, ultrasonic method simplify the process, shorten time and improve efficiency compared to the sol-gel method.Finally, the synthesis of TiO2/SiO2/Graphene Oxide composite nanoparticles and their subsequent loading on fibres in a one-step process exhibited significant antibacterial property and superhydrophilicity. At the same time, water droplets only took 450 ms to spread on the surfaces of coated fabrics and antibacterial rate is also above 99%. Furthermore, the antibacterial properties remained after 30 launderings, indicating excellent washing durability. Meanwhile, this process had no significant negative effect on the tensile strength and air permeability of sonotreated fabrics.Therefore, based on the excellent photocatalytic degradation, self-cleaning ability,antibacterial capability and durability of TiO2/Si O2/GO coated fabrics, if they are applied for textiles, especially in the field of medical textiles, they will provide a huge advantege in society. |
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